Someone mentioned my coolant temp, if you read through, I had made a mistake (well not really cause I did say something along the lines of I believe or recall and could be wrong) ,so my coolant is well within range and I had posted the specs above.

I do not smell gas at all.

Does anyone know if a heavy strain on the alternator could throw everything off this much? System was put in end of September. Running around 1500 watts rms.

Also, although one person has told me this is the case...anyone know if 04 jgc have the little silver disk/flap in the gas fill tube? When I pop my cap off, there is no little silver flap to push through when filling up. Someone said its lower, but if like to be sure.
Maybe half my gas is evaporating? Lol
Thanks

I just got my 04 WJ a month or so ago, and I do NOT notice a little flap. My 99TJ has one, but I don't see on on the WJ. I'm not sure why. I haven't really looked that closely at it to see if it's lower in the tube.

Hope that helps.

As for the stereo, run for a tank or 2 without the amp. See it if goes up.

It's been cold in New York since November. How long do you let the WJ idle to remove ice and snow? Idling kills fuel mileage. I had a car that would lose 5 mpg in the winter due to me letting it warm up for ice and snow removal back when i lived in Ohio.

Like 86CJ says, fill up the tank, take it for a decently long ride. Fill up the tank again and calculate fuel mileage. See if it improves.

Any chance a brake or two could be sticking? Any funny smells at all after a long drive? Does it still feel like it has the same pickup it used to? Tire pressure is normal? Have you done a reset of the ECU?

If fuel isn't leaking and the exhaust doesn't smell any different, then something has got to be adding resistance, I would think.

86cj, curious. Why would you suggest a 40 drive and then refill? Thinking evap or something while it sits? Like theft? I know its not theft, but it is a good idea. Curious on what made you suggest it?

Brad, I have days where I remote start, but it doesn't sit longer than if I had gotten in and sat for a few minutes. I also have days where I may sit idle for 10 minutes with a coffee somewhere, no drastic changes. I will test the theory though as right now I will not rule out anything that hasn't been checked. Hence this is a week to week thing I check because I will do a "fix" and drive for a week to test said "fix"...so that will be on the list.

Crawling, nothing dragging...at least not the brakes or a body under the car. Speaking of bodies, nothing new or heavy in the "trunk" area.

Funny smells. Funny you mention that. While investing a slight hissing under the good today, thought vac but I think it's just the norm for the throttle body at idle...I did notice a smell on the passenger side in the engine compartment. Couldn't quite out my finger on it. Didn't smell like any real fluid smell. The only random thing I can think of at this moment is straight up exhaust before it hits the cat and muffler? This is just a long shot guess.
Tires are all right.
If by reset the ecu you mean disconnect battery ten Mounties, out back, yes. Maybe just maybe that gained me 1-2 mpg over 70 miles over the course of a week...maybe, but I haven't done it in a testing fashion.

Great ideas guys. Appreciate it very much and would love to peg this and do a write up including all the ideas...once I've got a final chapter for said write up. Lol

The 40 miles drive is arbitrary. It is just a number the gist is to fill it up and drive it then top off and calculate milage and see if its 6 mpg yet or a different number.

My wife, in the winter, goes out and starts our WJ. Comes in and eats breakfast, then drives 3/4 mile to our business. Care to guess what that equals in gas milage for a tank average if no other trips were made during that tank?

Sorry I wasn't clear about the 40 miles, it wasn't the number, more so the idea of filling driving filling again.

Looking back at my records I had a day I filled up, drove the miss to work, drive back 45 miles round trip, filled up and got...ready...14mpg. Now it was 99% highway, driving up normal, driving back without her in the car was a heavy in the pedal white knuckle drive back.
So...although that may be a little low for highway, I am wondering if it it's relative or not. Tomorrows weather is going to suck, so I think I am going to fill it and do and 80 mile drive Wednesday and then ill fill it again and see.
I am curious. Would be nice to see if its an over night evap kinda thing or just a city driving thing.

Also, if you don't mind...I had some scanner questions above, if someone could assist with those, that would be great.

Tomorrow I am going to see if I can figure out the manifold pressure to see if it appears correct. I see a lot of map sensor issues effecting mileage, so maybe that's it??

Here is a link to a site that lists the most common mechanical problems for bad MPG. One of the listed problems is the eng. temp sensor which reminded me of a problem I had on a Dodge Van once. The temp sensor reversed its coefficient and caused the eng. to run rich, it was telling the computer that it was colder, requiring more fuel. Just a thought.